The power went out in our neighborhood for 24 hours earlier this week, but we had a lot of battery-powered LED lights. These bulb-shaped ones are meant from camping, but you can hang them from chandeliers, curtain rods, hooks, etc. (I might make an adapter with my 3D printer so they can screw into bulb sockets.) They use 3 AAA batteries. They're on sale on Amazon: 2 for $8.